Nokia had monopoly in many European countries with over 80% market share and still do have in some places, but especially Samsung is moving fast currently. It's very common to go and just buy the newest Nokia.
Thought you are right there's no real global monopoly.

One thing that's a bit worrying what North America is bringing is the carrier control. Service providers need strong unlocked market next to them and some strong mobile phone manufacturers who can push example VOIP and other services.

Things change Nokia have been the top gun for 9-10 years and dominated for past 4 years. It's time for fresh ideas and clean the field. Maybe in 2 years Symbian^4 with Qt and Harmattan will make Nokia again far target for it's competition in smartphones maybe Apple will form portfolio of phones and crasp big amount of mid end market too or maybe Samsung who is the one really growing will make Android it's babey and take the smartphone market where it's stil small player.